The Role of CEC and pH in Cd Retention from Soils of North of Iran

Abstract

Cadmium (Cd) is a critical environmental chemical in which sorption reactions control its entry into soil solution. The aim of the present study was to evaluate Cd sorption characteristics of some soils of the northern part of Iran with a wide range of physicochemical properties. Duplicates of each sample were equilibrated with solutions containing 5 to 500 mg Cd L -1 with 0.01 M CaCl 2 as background solution. The quantity of Cd retention was calculated as the difference between initial and equilibrated Cd concentration. Sorption isotherms including Freundlich, Langmuir, Temkin, Dubinin-Radushkevich, and Redlich-Peterson were used to evaluate the behavior of Cd sorption. Cadmium sorption data were well fitted to Langmuir, Freundlich, and Redlich-Peterson isotherms. The constant of Freundlich equation (k F ) and adsorption maxima (b L ) of Langmuir equation were related to pH and cation exchange capacity (CEC). The maximum buffering capacity (K d ) was significantly correlated with pH (R 2 =0.52, p≤0.001) and calcium carbonate equivalent (CCE) (R 2 =0.63, p≤0.001).Redlich-Peterson constants (k RP and a RP ) were significantly correlated with pH (R 2 k RP =0.30, p≤0.007) and (R 2 a RP =0.27, p≤0.012). It seemed that pH, CEC, and CCE were the main soil properties regulating Cd retention behavior of the studied soils.

Immobilization of Cadmium by Molecular Sieve and Wollastonite Is Soil pH and Organic Matter Dependent

“…Figure 5 and Table 4 A also indicate that soil CEC was positively correlated with soil available Cd. OM, as the main sorbent in soil [ 45 ], exhibited a significant positive correlation with CEC in this case ( r = 0.344 **, p < 0.01; Figure 5 ). The reason for the positive correlation between OM and available Cd may also explain why CEC was positively correlated with soil available Cd.…”

Intercropping with herbs minimizes cadmium availability through altering physicochemical dynamics and metabolite profiles in wheat rhizosphere

“…The effect of intercropping treatment also showed in cation exchange capacity, which reflected the soil fertility retention capacity, increasing by 5.16%–32.26% leading to the better growth of plants showing in the form of higher biomass. Frost and Griffin (1977) reported that high pH, high CEC of soils may have favoured the conditions for low Cd availability (Esfandbod et al, 2011), confirming that high CEC was conductive to reducing Cd effectiveness. Treatment in the middle of this experiment may cause changes in soil salinity, resulting in an increase in wheat biomass and a decrease in Cd content.…”